Electric heater



Jan. 6. 1925. 1,522,206

W. A. RA N K! N ELECTRI C HEATER Filed, Aug. 30, 1921 a g am! 7. /7 F 4A!" nlmumml K I V i /8 Inventor:

'/ f F/ 33 B H a /9 20 Willi m ARamKin, by

* His Attorney.

Patented J an; 6, 1925.

UNITED STATES WILLIAM A. RANKIN, O'F OAK l-ARK, ILLINOIS, ASSIGNOR TOEDISON ELECTRIC AI PATENT OFFICE.

PLIANCE COMPANY, INC., A CORPORATION 01? NEW YORK;

ELECTRIC HEATER.

Application filed August 30, 1921.

To all whom it may concern Be it known that-I, WILLIAM A. RANKiN, acitizen of the United States, residing at Oak Park, in the county ofCook, State of 5 Illinois, have invented certain new and usefulImprovements in Electric Heaters, of which the following is aspecification.

My invention relates to electric heaters and has for its object theprovision of simple and reliable means for holding the heating elementin place.

More specifically, my invention relates to heaters of the type in whichthe heating element is laid in a groove in a support of suitable heatrefractory insulating material. It is desirable in heaters of this typeto have the heating element exposed to a large extent for heatradiation, while at the same time some means must be provided forengaging the heating element to hold it in place in the groove. Theprevious custom has been to shape the sides of the groove so as tooverhang the heating element either along the entire length of thegroove or at intervals. This construction has the disadvantage that theheating element must be threaded in place in the groove or bent' ordistorted so as to be forced between the overhanging portions into placein the groove. Such constructions also have the disadvantage that theheating element can be removed only with considerable (lli'llculty.

In carrying out my invention, I mount the heating element in'a spiralgroove in one face of a disc of heat refractory insulating material. IThis spiral groove instead of having the usual smooth curvedconfiguration is polygonal in form. At the 40 angles of the groove wherethe sides join Ihave provided overhanging portions and "correspondingrecesses in'the opposite walls, respectively, of the groove: By means ofthis construction I am enabled to freely,

insert the heating element in place in the grooves so as 'to be heldunderneath the overhanging portions, and the unit may be easily removedat any time for renewal or repair. I have provided apertures throughSerial No. 496,854.

the insulating support for the terminals of the heating element andheaded members, to which the heating element is attached, adapted to beseated in the apertures. The headed members are held in place in theapertures by means of stiff metallic leads. provided with terminals,which extend through the support and are bent against the opposite sideso as to hold the headed members in place." The heating element may beformed with the terminals and leads attached ready to be put inplace inthe insulating support. By means of this construction I have providedavery simple and reliable electric heater in which the heating elementmay be easily replaced or renewed without the necessity of makingsoldered or brazed connections for theterminals.

Referring to the drawings, Fig. l is a section through the line :1, 1 ofFig. 2, looking in the direction of the arrows, showing an insulatingsupportconstructed in accordance with my invention; Fig. 2 is a viewshowing the various parts of the electric heater; Fig. 3 is a sectionalassembly view along the line 3, 3 of Fig. 2, looking in the direction ofthe. arrows; while Fig. 4 is a view showing a modified form ofconnection for the heating element.

Referring to the drawing, a disc 10 made of a suitable heatrefractoryinsulating material is provided with a spiral U shaped groove11 in its upper face in which the helical heating element 12 issupported. The groove is also polygonal in form, being shown in thedrawing as six sided or hexagonal. At the angles, or corners, of thehexagon the inner and outer walls-0f the groove are provided,respectively, with overhanging portions 13 and recesses 14;. In elfectthe groove is inclined outward at the angles or corners. struction thewidt of the groove is maintained substantially uniform throughout itslength and depth so that the heating element can be easily slipped inplace in the groove underneath the projections 13 which hold it inplace. The heating element is preferably held in the groove undertension in By means of this conorder to positively separate the turnsfrom one another and cause the element to cling to the inner wall of thegroove underneath the overhanging portions.

The groove is in the form of a double spiral. Apertures for the terminalleads of the heating element are provided through the disc at each endof the groove and at the center. These apertures are elongated andconsist of round openings and slots 16 intersecting therewith andextending longitudinally along the center of the groove; As shown inFig. 3, headed members 17, to which the heating element 12 ispermanently attached, are adapted to be seated in the round portions 15of the apertures, the gnome being enlarged at 15 around holes 15 for theinsertion of the heads of the members. Leads 18 of stiff metallicmaterial are attached to the headed members 17 and extend through theapertures. Flat terminal blades 19 are attached to the ends of theleads. The elongated portions 16 of the apertures are adapted to permitterminals 19 to pass therethrough to effect the insertion or removal ofthe heating element.

An insulating disc 20 of suitable heat refractory insulating material isprovided adjacent the lower face of the disc 10. The upper surface ofdisc 20 isconcave to form an air space and to provide Space for leads 18which are bent against the lower face of disc 10 to bring terminals 19in position to be inserted through holes 21 in disc 20, which forms asupport for the terminals. The upper ends of the terminals 19 areenlarged to provide shoulders 19 which are held tightly between disc 10and insulating plate, 20. The terminals 19 proj ect through theinsulating plate 20 for the attachment of-suitable connectors -for theheating circuit.

A metallic casing-22 is provided to retain thedisc 10 and the insulatingplate 20 in fixed relation with respect to each other. To assemble theheater the insulating disc 20 is placed in casing 22;and'then the disc1Q with the heating element and terminals in proper position is put inplace. It will be observed that the headed members 17 are held in placein holes 15 by the stiff leads 18 connected, respectively, thereto, theleads beingbent so as to seat the headed members in holes 15. The unitmay be held together by suitable bolts 23 passing through alined holesin the discs and the casing.

The heating element 12 is preferably constructed of a coiled length ofresistance conductor, and it can "be formed, as shown in Fig. 2," withthe terminals permanently attached to each endand the middle thereof.The operation of inserting and removing the heating element can beeasily accomplished. Three terminals have been disclosed for the heatingelement so that a plurality of operating temperatures may be obtained bysuitable switching mechanism in a well known manner.

In Fig. 4 I have, shown a modified form of connection between the headedmembers and the heating element and leads. The headed member is providedwith two parallel holes 24 through which the ends of both the heatingelement and the lead are threaded. A brazed joint is then made. Thisprovides a very reliable and permanent connection for the terminals ofthe heating element.

Small rectangular apertures 25 are pro vided in the insulating disc 10directlybelow the projections 13. These apertures are found to benecessary to facilitate the forming of the disc. An aperture 26 isprovided in the insulating plate 20, and an inclined slot 27' leads fromthe center of the insulating plate thereto. The aperture 26 is providedfor the purpose of draining away an liquids which have been spilledthrougi carelessness or otherwise on the upper surface of the heater anddrip through apertures 25 to the insulating plate. This system of drainsalso facilitates the cleaning of the heating unit.

Various changes and modifications will appear to those skilled in theart. Obviously, a rigid form of heating element can be used as well as aflexible coil element since the construction of the grooves permits theready insertion of any type of heating element. Furthermore, it iscontemplated within the scope of this invention that the resistanceconductor may be permanently connected directly to the terminal bladeswithout the interposition of the headed members and conducting leads.

In accordance with the provisions of the patent statutes, I havedescribed the principle of operation of my invention; together with theapparatus which I now consider to represent the best embodiment thereof,but

I desire to have it understood. that the apparatus shown is onlyillustrative and that theinvention can be carried out by other means. Y

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is

1. An electric heater comprisin a support provided with a groove, ofsald groove being provided with overhanging portions and cooperatingrecesses at intervals, each overhanging portion having a corres ondingoppositely disposed recess, and a eating element supported in saidgroove and held therein by said overhanging portions.

2. An electric heater comprising a support of heat refractory insulatinmaterial provided with a groove, the side walls of said groove being Iprovided with overhanging the slde walls portions and cooperatingrecesses at intervals, each overhanging portion having a correspondingoppositely disposed recess, and a coiled resistance conductor supportedin said groove and held therein by said overhanging portions.

3. An electric heater comprising a support of heat refractory insulatingmaterial provided witha spiral, polygonal groove, the side walls of saidgroove being provided with overhanging port-ions and cooperatingrecesses at the angles thereof, and a coiled resistance conductorsupported in said groove and held therein by said overhanging portions.

4. An electric heater comprising a support, provided with a groovehaving substantially parallel inclined side walls at intervals, and aheating element supported in said groove and held therein by saidinclined side walls.

5. An electric heater comprising a support of heat refractory insulatingmaterial provided with a groove having substantially parallel inclinedside walls at intervals, and a coiled resistance conductor supported insaid groove and held therein by said inclined side walls.

6. An electric heater comprising a support provided with a groove, aheating element in said groove, said groove having substantially'parallel side walls inclined at intervals so as to secure the heatingunit in place.

7. An electric heater comprising a casing, a pair of plates of heatrefractory material in said casing, one of said plates being providedwith a'groove, a resistance conductor supported in said groove, andterminals for said resistance conductor extending through the otherplate and clamped between said plates.

8. Anelectrie heater comprising a. support of heat refractory insulatingmaterial provided with a groove and a plurality of apertures, aresistance conductor in said groove, a plate of insulating materialadjacent said support provided with apertures, terminal membersextending through the apertures in said plate and provided with headsclamped between the support and plate, metallic leads extending throughthe apertures in said support and connecting said terminal members tosaid resistance conductor, and means for securing said plate and supporttogether whereby the terminal members are secured.

9. An electric heater comprising a support of heat refractory insulatingmaterial provided with a groove and a plurality of apertures, aresistance conductor supported in said groove, a plate of insulatingmaterial adjacent said support provided with apertures, and terminalmembers connected to said resistance conductor through the apertures insaid support extending through the apertures in said plate and clampedbetween said support and plate, said terminal men1- bers being arrangedto be passed through the apertures in said support to effect the removalof the resistance conductor and terminals together. a

10. An electric heater comprising a support of heat refractoryinsulating material provided with a groove and -a plurality ofapertures, a resistance conductor supported in said groove, a plate ofinsulating material adjacent said support provided with apertures,terminal members seated in the apertures in said plate and provided withheads clamped between the support and plate, and leadsextending throughthe apertures in said support permanently connecting said terminalmembers to said resistance conductor, said terminal members beingarranged to be passed through the apertures in said support to effectthe removal of said resistance conductor.

11. An electric heater comprising a support of heat refractoryinsulating material provided with a groove and a plurality of apertures,a resistance conductor, in. said groove, terminal members, a support forsaid terminal members, and stiff bendable leads connecting said terminalmembers to said resistance conductor through the apertures in saidsupport, said leads being bent so as to secure said resistanceconductor.

12. An electric heater comprising a support of heat refractoryinsulating material provided with a groove and a. plurality ofapertures, a resistance conductor supported in said groove, a plate ofinsulating material below said support provided with apertures, terminalmembers extending through the apertures in said plate clamped betweenthe plate and support, and stiff bendable leads connecting said terminalmembers to said resistance conductor through the apertures in saidsupport, said leads being bent so as to secure the ends of theresistance conductor when the terminal members are secured.

13. An electric heater comprising a support of heat refractoryinsulating material provided with a groove, and a plurality of aperturesintersecting said groove, headed members seated in said apertures, aresistance conductor supported in said groove and connected to saidheaded members, stiff metallic leads connected to saidheaded members andextending through said apertures, terminals on said leads, and a supportfor said terminals, said leads being bent so as to secure said headedmembers in said apertures.

14. An electric heater comprising a support of heat refractory insulatinmaterial provided with a groove, and a p urality of aperturesintersecting said groove, headed members seated in said apertures, acoiled resistance conductor sppported in saidgroove and permanentlyconnected to said eaded members, leads of stiff metallic materialpermanently connected to said headed members and extending through saidapertures, terminals secured to said leads, and means for supportingsaid terminals, said leads being bent so as to hold the headed membersin position in said apertures, said apertures being adapted to permitthe terminals to pass therethrough to effect the 10 removal of theheating element.

In witness whereof, I have hereunto set my hand this 24th day of August,1921.

WILLIAM A. RANKIN.

